Nowadays, a large variety of different content formats are known and utilized in different applications. For example referring to audio codecs, several codecs as for example WAVE (WAVE=waveform audio format used by Microsoft Windows and IBM), MPEG4 (MPEG=moving pictures expert group), MP3 (MP3=MPEG-1 layer 3), AAC (AAC=advanced audio coding) etc. are different codecs, making use of different coding algorithms. With respect to mobile applications, i.e. usage of mobile phones, PDA (PDA=personal digital assistant), portable computers, etc. not all available content formats can be supported. This is due to the fact that portable devices lack of processing power and memory resources that advanced content formats necessitate for decoding. As part of the state of the art, a user trying to access content, which is available in a format that is not decodable on the corresponding device, uses a transcoding entity to change the coding algorithm of the desired content to a format that the user can decode on his device. In order to do so the user has to download or to retrieve the desired content, which he cannot decode. Once the content is available on the user's device, the user provides the content to a transcoder, which changes the coding algorithm of the content, and in turn provides the transcoded content to the user.
FIG. 4 illustrates an example of the mechanism described above. FIG. 4 shows a sink 410 trying to access a certain content available at a content source 420. FIG. 4 displays a message sequence chart of the state of the art transcoding procedure. In a first step the sink 410 browses the content directory available from the content source 420. Once the sink 410 has found the desired content, it gets the available resources for the content directory object. Although the resource of the desired content indicates to the sink 410 that it cannot decode the content, it gets the content from the content source 420. Since the sink 410 is not capable of decoding the content, which can for example be due to lacking processing or memory resources, the sink 410 requests a transcoding of the content from the transcoder 430. After the transcoder has acknowledged the transcoding of the content the sink 410 now provides the available content to the transcoder 430, upon which the transcoder 430 can provide the transcoded content to the sink 410.
As indicated by the transcoding example illustrated in FIG. 4, the state of the art procedure necessitates a lot of data transfer. First, the sink 410 has to download the content, although it is not capable of decoding it, then it has to upload the content to the transcoder 430, and finally the transcoder 430 has to upload the transcoded content to the sink 410. The state of the art procedure is very disadvantageous, as it necessitates a huge amount of data transfer, it is very inefficient and very time intensive.
With the state of the art procedures, user satisfaction is very limited. Especially for real-time applications, the state of the art procedure is not feasible.